Environment-friendly friction material composition

Abstract

Friction material that is substantially free of elemental metals, metal alloys, and antimony trisulfide, wherein the solid lubricant includes a metal sulfide. The disclosed compositions of the friction material are believed to be more environment-friendly than conventional compositions. However, the substantial elimination of elemental metals, metal alloys, and antimony trisulfide from the disclosed compositions is performed in a manner that does not appear to substantially impact the friction performance and noise behavior of the corresponding brake components. Moreover, it is believed that at least some of the disclosed compositions increase the useful lifespan of the brake components and reduce wear of the rotors. The longer brake-components lifespan and lower rotor wear provide additional benefits in terms of reducing non-exhaust-related vehicle emissions, which further alleviates the environmental impact of traffic emissions.

What is claimed is: 
     
         1 . A friction material for a brake system, the friction material comprising:
 about 1.0% to about 10.0% by weight of a solid lubricant including a metal sulfide;   about 6.0% to 15.0% by weight of a binder;   about 2.0% to 15.0% by weight of an abrasive; and   one or more fillers; and   wherein the friction material is substantially free of metal and metal alloy in one or more forms selected from the group consisting of a fiber form, a chip form, and a powder form.   
     
     
         2 . The friction material of  claim 1 , further comprising less than about 20.0% by weight of non-metal fiber. 
     
     
         3 . The friction material of  claim 2 , wherein the non-metal fiber is selected from the group consisting of cellulose fiber, aramid fiber, polyacrylonitrile fiber, acrylic fiber, cotton fiber, ceramic fiber, and mineral wool fiber. 
     
     
         4 . The friction material of  claim 1 , wherein the one or more fillers include one or both of an inorganic filler and an organic filler. 
     
     
         5 . The friction material of  claim 4 , wherein the inorganic filler is selected from the group consisting of barium sulfate, wollastonite, talc, titanate, calcium carbonate, calcium fluoride, lime, coal, graphite, coke, activated carbon, glass bubbles, glass beads, and vermiculite. 
     
     
         6 . The friction material of  claim 4 , wherein the organic filler is selected from the group consisting of melamine dust, polymerized cashew nut shell liquid dust, ground rubber particles, and cellulose. 
     
     
         7 . The friction material of  claim 1 , wherein the friction material is substantially free of one or both of the metal and the metal alloy in any form. 
     
     
         8 . The friction material of  claim 1 , wherein the friction material is substantially free of antimony. 
     
     
         9 . The friction material of  claim 1 , wherein the metal sulfide includes a transition metal sulfide or a post-transition metal sulfide. 
     
     
         10 . The friction material of  claim 1 , wherein the metal sulfide includes a sulfide of a monovalent metal, a sulfide of a divalent metal, a sulfide of a trivalent metal, or a sulfide of a tetravalent metal. 
     
     
         11 . The friction material of  claim 1 , wherein the metal sulfide is selected from the group consisting of an iron sulfide, a zinc sulfide, a bismuth sulfide, a manganese sulfide, and a tin sulfide. 
     
     
         12 . The friction material of  claim 1 , wherein the binder comprises phenol-formaldehyde resin. 
     
     
         13 . The friction material of  claim 1 , wherein the abrasive is selected from the group consisting of alumina, magnesium oxide, zirconia, zirconium silicate, silica, silicon dioxide, silicon carbide, mullite, mica, iron chromite, calcium magnesium silicate, calcium zirconium silicate, calcium magnesium aluminum silicate, and magnesium aluminum silicate. 
     
     
         14 . The friction material of  claim 1 , wherein the friction material consists of, in total of 100% by weight:
 about 4.0% to about 7.0% by weight of the solid lubricant;   about 8.0% to 11.0% by weight of the binder;   about 6.0% to 12.0% by weight of the abrasive;   about 5.0% to 9.0% by weight of non-metal fiber; and   about 65.0% to 73.0% by weight of the one or more fillers.   
     
     
         15 . The friction material of  claim 1 , wherein the binder provides a thermosetting matrix to hold together at least the solid lubricant, the abrasive, and the one or more fillers. 
     
     
         16 . A brake member for an automotive vehicle, the brake member comprising the friction material of  claim 1 . 
     
     
         17 . A brake system for an automotive vehicle, the brake system comprising:
 a rotor disk; and   a brake member comprising the friction material of  claim 1 .   
     
     
         18 . A friction material for a brake system, the friction material comprising:
 about 1.0% to about 10.0% by weight of a solid lubricant including a metal sulfide;   about 6.0% to 15.0% by weight of a binder;   about 2.0% to 15.0% by weight of an abrasive; and   one or more fillers; and   wherein the friction material is substantially free of elemental metal and metal alloy.   
     
     
         19 . The friction material of  claim 18 , wherein the friction material is substantially free of elemental metal and metal alloy selected from the group consisting of elemental iron, steel, elemental tin, elemental zinc, elemental copper, elemental aluminum, elemental lead, elemental titanium, tin alloy, zinc alloy, copper alloy, aluminum alloy, and magnesium alloy. 
     
     
         20 . The friction material of  claim 18 , further comprising less than about 20.0% by weight of non-metal fiber.